EVGA 750W G2 80+ Gold -> X2 Cap Burnt

[foetusmachine]

Hi all,

Might not be a query specific to the PSU itself, but detail provided, just in case.

My PSU virtually caught fire last night. Thankfully I could smell magic smoke, just before I went to bed. Magic smoke is not a common thing where I live, and if I can smell it, I can be 90%+ sure it's something to do with me. Taking the PC outside, I dismantled the PSU and found what I think is the culprit:



The x2 cap had burnt (burned?) through both side and released the magic and left its white residue everyehere.

A few key points to note:

1. The PSU has a power saving mode where its internal fan is switched off until a certain load is reached. I had this activated.
2. The PSU is secondhand. I have no idea of its history.
3. Since I've been using it, it's been plugged in via a UPS.
4. I pulled the plug before the fuse blew.
5. I was unable to determine the actual value of the cap and have since found a 0.47uf X2 salvaged one in my drawers and replaced it.
6. I'm now back using the PC with the PSU's fan always on.

Questions:
Is this a expected failure mode of X2 caps?
The failed X2 cap pin spacing is ~15mm, but the PSU PCB has optional through holes to also accommodate a larger ~22mm X2 cap. Is there any benefit in me installing a physically larger cap?
Is there any benefit in using a higher rated cap (X1)?

Note: I will continue to use the PC behind a UPS.

Any input here would be great Thank you for listening to this many of my words!

Replacing the PSU with a new, warrantable unit - yes, thank you.

[fzabkar]

I would put it down to bad luck, although there have been some notable exceptions.

https://hackaday.com/2023/04/01/why-do-rifa-capacitors-fail/